Double-belt sanding machine



Nov. 29, 1927. 1,650,863

E. F. BUTTS DOUBLE BELT SANDING MACHINE Filed Aug. 20, 1925 2Sheets-Sheet l Nov. 29, 1927. 1,650,863

E. F. BUTTS DOUBLE BELT SANDING MACHINE Filed Aug. 20, 1925 2Sheets-Sheet Patented Nov. 29, 1927..

PATENT EMIL IE. BUTTS, OF TACOMA, WASHINGTON, ASSIGNQR "1'0GREGORY-BUTTS COMIEANY,

OF TACOMA, WASHINGTQNT, A. CGRPDBATION OF WASHINGTON.

IbOUBIiE-BELT SANDING MACHINE.

Application flied August 20, 1925. Serial No. 51,370.

This invention relates to woodworking machines and especially to thatclass known as belt sanders which are adapted to smooth the surface offlat or curved wood. The purpose of my invention is to provide meanswherein two sanding belts, one coarse and the other line, may be usedtogether whereby both the roughing and finishing of the wood may be doneat a, single hancng of the wood. in order to accomplish this generalpurpose the objects of this invention are to provide means for keep-inthe belts separate on the same pulley; means for tel-z ing up the slackin either of the belts should one stretch more than the other; both saidmeans to be adapted for use whether the sanding surface of the beltstare outward or inward; means for adjusting the spindle sanderattachment whereby the track of the belts thereon may be controlled;means for changing the tension of the belts on the spindle sander; andmeans whereby the belts may be operated around a much sharper curve onthe spindle sander than has heretofore been possible. Other objects areto provide such a machine which can be readily set up in a factory;which is cheap to build,

strong'and rigid in construction, easy to operate, and which effects avery great saving 0 in the cost of the work which it performs overprevious costs thereof.

I attain these and other objects by the devices, mechanisms, andarrangements illustrated in the accompanying drawings, in which- Fig. 1is a side view showing my machine in use as at double belt sander,showing also in dotted lines, the positions of the two belts when usedas a spindle sander; Figs. 2, 3, 4 and hare cross-sectionsadjacent the:driving pulley thereof, to illustrate the positions of the various partswhen the sanded surface faces outward (Figs. 2 and 3') or inward (Figs.4 and 5), or when the right-hzrnd belt (Figs. 2 and d) or the left-handbelt (Figs. 3 and 5-) is loosest; Fig. 6 is a perspective view of theparts inthe same positionsas shown in Fig. 2; Fig. 7 is: an endelevation of the spindle sander end of the machine, showing it arr ngedfor sanding a: very sharp curve; Fig. 8- is' a; side elevation thereof;Fig. 9 is a side elevation, partly in section, of a spindle sanderattachment, to illustrate its adjustment in the machine to control thetracking of the belts thereon; and

Fig. 10 is an elevation thereof' Similar numerals of reference refer tosimilar parts throughout the several views.

Belt sanding machines haveusually been of two main types; a long beltsanding machine in which the wood to be smoothed is flat and laid on atable under the sanded surface of the belt which is presseddown thereonmanually, and a short belt sanding machine, usually with the surface ofthe belt vertical, at one end of which the belt bends around a finedvertical edge, or spindle nittachment, against which a curved surfacemay be pressed. In my machine I have combined these two types into asingle Inacl iine thereby economizing in equipment and in: floor spaceoccupied thereby besides producing a machine capable of doing workhereto-fore impractical in any belt sander. Further, ithas been foundimpossible to operate a short-belt spindle sander when the spindleattachment gives a sharp corner to turn, for smoothing small inwardcurves because, when the belt is short it must be made very tight andwhen it is tight it will quickly wear itself and the spindle attachmentout-and therefore is of no practical value, but I have found that whenthe belt is long, as in my machine, the belt need no longer be tight butthat sufficient traction may be had when it is quite loose, and underthese conditions it easily turns a very sharp spindle attachment, evensharp enough to smooth a groove or inward. curve an eighth of an inchacross, thus my machine is enabled to do work which has hitherto beendone entirely by hand at great cost. Again, it has been foundimpractical to attempt to run two belts on. the same machine because onewould stretch more than the other, even when cut the same lengtlnandbecause one would. climb on top of the other when pass ing over thepulley, and my machine overcomes both of these difiiculties and thus enables a coarse and a line sand belt to be run side-byside so that thewood may be roughed and then finished with the same handling, timeaccomplishing a further sav ing in the cost of manufacture of all partson which the: machine is used. Also, on spindle sanders, I have. foundit to be of great practical importance to provide a means of adjustingthe position and angle of the spindle sanding attachment in order tocontrol the tracking of the belts thereon.

Referring now to the drawings :this machine is provided with a fixedpedestal 1, on which the driving shaft 2, rotated by a belt 3 or othersuitable means, is mounted and carries a broad drive pulley i thereon.At the other end of the machine, at a distance of some twelve or morefeet, is mounted a second fixed pedestal 5 on which the idle wheel 6 isadjustably mounted, as hereinafter described, and also a third pedestal7, adjustable in distance from the driving pulley 4 and carrying aremovable and adjustable spindle sanding attachment 8 at its upper end.Between these two ends I mount the two sanding belts 9 and 10, eachpassing over the driving pulley 1 and either over the idle pulley 6 orthe spindle attachment 8, or both of them. The belts 9 and 10 are of theusual sand belt construction and may .have their sanded surfaces inwardor outward, as desired, except that when the spindle attachment 8 isused, the sanded surfaces will always be outward for obvious reasons.

It is practically impossible to mount these belts with exactly equaltension in them and it is therefore necessary to provide a means forincreasing the tension of the slackest by forcing it to traverse aslightly longer path than the other belt. This is accomplished bypressing the fabric or unsanded side of the longest belt vertically outof the normal path as illustrated in Figs. 1 to 5, inclusive, at a pointadjacent the driving pulley 4; and engaging the belt after it leaves thesaid pulley 4. In order to accomplish this I use the following device :Abracket 11 extends out from the fixed pedestal 1 and an adjustable arm12 extends out from the end of the said bracket, said arm 12 beingsecured to the bracket by a bolt 13 passing through suitable holestherein and clamping the said parts 11 and 12 together in adjustedposition. A belt-pressing device, of special shape, is attachet to theouter end of the arm 12 by means of a bolt 14 passing through both ofthem as hereinafter described. This belt-pressing device comprises twohorizontal sections 15 and 16, the outer section 15 being in line withthe right-hand belt 10 and the inner section 16 being in line with theleft-hand belt 9, and these two parts 15 and 16 are connected togetherby means of a vertical oilset section 17. Each part- 15 and 16 isprovided with a belt-engaging semicylindrieal block 18 and 19,respectively. These blocks 18 and 19 are mounted on opposite sides ofthe said parts 15 and 16 in such manner as to make their curved surfacesas far apart vertically as possible, that is to say, they increase. theoffset due to the section 17. The inner end of the part 16 is providedwith a lug 20 which extends at. right angles therefrom in the samedirection as the block 19 and slightly removed from the end of the saidpart 16, while a second lug 21 extends at right angles in the oppositedirection and is positioned at the end of the said par l6. Either one ofthese lugs 20 and 21 are adapted to lie on the outer side of the arm 12and to be attached thereto by means of the said bolt 14.

A brief examination of thi device shows that the part 16 may lie eitherabove the arm 12 (Figs. 2 and or below it (Figs. 4 and hen the sandedsurface is on the outside of the belts 9 and 10 then it is necessarythat the blocks 18 or 19 engage the upper surface of the belt and thesaid part 16 is placed above the said arm 12; but when the sandedsurface is inward, then the blocks 18 or 19 must engage the lowersurface of the belt and the said part 16 is placed below the said arm12. Also, it will be observed, that the two lugs 20 and 21 are offsetfrom each other laterally or horizontally. In order to permit theadjacent edges of the two belts 9 and 10 to come quite close to thecenter plane of the pulley etand to permit the blocks 18 and 19 toengage across their entire surface. not permitting their inner oradjacent edges to lap over the inner edge of the blocks in contacttherewith, I place the blocks 18 and 19 so that their inner edgesslightly overlap each other, by substantially the thickness of theoffset part 17. For this reason it is necessary to displace the devicelaterally, so that when the lefthand belt 9 (Figs. :3 and is engaged,the apparatus is pushed towards the left by being fastened to the arm 12by the right-hand lug 20, or when the right-hand belt 10 is engaged(Figs. 2 and 4) the device is displaced towards the right by beingfastened to the arm 12 by the lefthand lug 21. In this way the apparatusis shifted to engage across the entire surface of the stretched belt andyet to be well free from the edge of the other or tight belt. Theadjustment of the arm 12 about the bolt 13 controls the extent that theblock 18 or 19 pushes the belt 10 or 9, as the case may be, out of thenormal path to tighten it.

In order to keep the belts 9 and 10 separate on the pulley I mount, onthe same bracket 11, a vertical plate 2 having a long slot 23 therein,through which the same bolt 13 passes. This plate therefore adjustablevertically on the bracket 11 and is held in vertical position by ashoulder 2-1; on the said bracket. A diamoiul-shapcd separator 25 ismounted on the end of a horizontal extension of the plate 22. Thevertical points of this separator 25 are positioned directly in linewith the cent r of the pulley at and engage the inner edges of the twobelts 9 and 10 just before they reach the saidpulley. .In Figs. 1, 2,3and 6 this separator is shown in its lowered position, wherein itengages theund'er or: unsanded surfaces of the said two belts,-while inFigs. l and is shownraised in order to engage the upper or unsandedsurfaces. thereof. Thus it will be seen that-the separator 25 preventseither belt 9 or 10 from reaching the central plane of the pulleys:andtherefore keeps tliemseparate, the one from the other. lit lealsoevident that-a further adju tment of the plate 22 will raise orlower the said separator 25 toincrease or decrease the distance thatthe'sa1d belts travel apart.

sanded surfaces are outward or inward thereon.

The third'pedestal 7 shaped so that its lower end is substantially inline with the pedestal 5 while it carries the spindle sander 8 at apoint above and well removed from the pulley 6, thus giving room for theworkmans feet when using the spindle sander 8, and (shaped at its upperend to span the said idler pulley 6 so thatit may be adjustedindependent of its position-relative to the said pulley 6. The pedestal7 rides on a pair of guide tracks 29, one of which may be provided withrack teeth 30 into vhioh a pinion 31, carried by the pedestal 7, meshes.This pinion 31 is turned by the hand wheel 32. The pedestal 7 may beclamped in adjusted position by the clamp screws 33 which are mounted inthe said guide tracks 29 and pass through slots in the base of the saidpedestal 7. The adjustment of the said pedestal 7 controls the tautnessof the belts 9 and 10 in passing over the spindle sander 8 carriedthereby.

The upper ends of the tines of the Y shaped pedestal 7 are cut to formrectangular extensions or lugs 34. These lugs 34: enter slots 35 in across bar 36 of the sanding attachment 8. Usually this cross bar 36extends straight across from one tine to the other (Figs. 1, 9 and 10)but when the spindle sander attachment is arranged for a very sharpcurve this bar may be offset (Figs. 7 and 8) to permit the belts 9 and10 to pass directly thereunder from the drive pulley l; otherwise Iusually pass the belts 9 and 10 around the idler wheel 6 and then aroundthe spindle sander attachment, as seen in curvature.

dottedlines in Fig. 1. The bar 36 rests on shoulders 37 011 the tops ofthe tines of the pedestal 7, formed by the rectangular lugs 13%, andadjustable atbolth ends by means of two pairs of set screws 38 engagingthe front and rear faces of the saldlugs 3%.

[thus by adjusting the righthand end of the bar 36 forward and theleft-hand end thereof rearward the said bar 36 is twisted slightly outof the normal alignment; or by adjusting them both equally forward orbackward the. belts may betightened or loosened as desired. I w

I prefer to have the spindle sander attachment removably secured to thebar 36,

though in the special case of the sharp edge as. above described the barand the attachment may be formed of one piece, or permanently attachedtogether.- As shown in Figs.

9 and 10 this attachment comprises a base 39 having slots l0 to engagethe fastening bolts ll by which it is removably secured to the.cross-bar 36. This base 39 carries a block 42 of the desired shape. Theblock l2. has a working surface 43' of the requisite The block 42 iscoveredv by a layer-of felt 4A, and this felt is in turn covered bycanvas 4.5 thoroughly impregnated with glue to give it the requiredwearing qualities. The belts .9 10 pass around the curved part 43 withtheir sanded faces outward and are adapted to'smooth an inwardcurve orgroove. The part to be thus smoothed is held by the operator against thecurved part 43, first using the rough sand belt and then shifting itlaterally to engage the liner sand belt whereby it is finished.

Having, therefore, described my invention, what I claim is J 1. A doublebelt sanding machine, comprising a driven pulley; a pair of endlesssanding belts riding thereon and driven thereby; means supporting theother ends of the loops of said endless belts; and transverselydiverging separator means adjustably supported adjacent the pulley anden gaging the belts as they approach the pulley, whereby the extent ofthe separation of the belts may be controlled.

2. A double belt sanding machine as set forth in claim 1, wherein saidendless sanding belts have one side sanded; and wherein said separatormeans comprises a V-shaped body having the point of the V insertedbetween the belts, whereby the edges of the belts engage the sides ofthe V-shaped body with the unsanded sides.

3. A double belt sanding machine as set forth in claim 1, wherein saidendless sanding belts may be mounted with their sanded sides inward oroutward on said pulley; and wherein said separator means comprises arhombus-shaped bodywith its sharp points vertical and which isvertically adjustably sanded sides of the belts.

4. A double belt sanding machine comprising a driven pulley; a pair ofendless sanding belts riding thereon and driven thereby; adjustablemeans supporting the other ends of the loops of said endless belts,whereby their tautness may be controlled; means adapted to keep the twobelts separate; a supporting arm having an upper and a lower surface;and a belt-pressing device secured to said arm on either said upper orlower surfaces, and comprising a block which when it is secured to theupper surface of the supporting arm projects downward and is adapted topress downward on the upper side of either one only of the belts, andwhen it is secured to the lower surface of the supporting arm projectsupward and is adapted to press upward on the under side of either oneonly of the belts, whereby the slacker of said two belts may be pressedupward or downward to bring its tautness to substantial correspondencewith that of the other belt.

5. A double belt sanding machine as set forth in claim 4, wherein saidbelt-pressing device is reversible and comprises two blocks mounted onits opposite sides, said blocks being ofi'set laterally from each otherto come into alignment with the two belts respectively, whereby when thedevice is mounted in one position one block engages one belt to take upits slack while if it is mounted in its reverse position the other blockengages the other belt to take up its slack.

6. A double belt sanding machine as set forth in claim 4, wherein saidbelt-pressing device is reversible and comprises two blocks mounted onits opposite sides, said blocks being oflset laterally from each otherto come into alignment with the two belts res ctively; together withsecuring lugs exten ing from the two sides of said belt-pressin device,said lugs being offset laterally rom each other, whereby when the leftblock is positioned to engage the left belt the beltpressing device isdisplaced toward the left and when the right block is positioned toengage the right belt the belt-pressing device is displaced toward theright, thereby in each case drawing any portion of the beltpressingdevice out of contact with the other belt.

EMIL F. BUTTS.

